Design, Modelling and Force Control of 9-DOF Hybrid Redundant Polishing Robot for Unknown Contour Surface

The work involved the construction of a hybrid redundant polishing robot and the development of an adaptive fuzzy polishing control technique for robot follow-shape constant force polishing. The objective was to enhance the robot's ability to manage force and position while polishing workpieces with unclear characteristics. The hybrid polishing robot is comprised of a redundant configuration, with a parallel polishing mechanism mounted on a serial manipulator. The hybrid polishing robot consists of a position control serial mechanism and a force control parallel mechanism. The series manipulator is utilized to execute the movement of the polishing trajectory, while the parallel polishing end-effector is employed for the real-time adjustment of contact force. Within the subsystem of the parallel force control mechanism, we have developed an adaptive fuzzy control technique that relies on a low-dimensional T-S fuzzy model and impedance model. This method mitigates the deviation resulting from the uncertainty of the workpiece and accomplishes reliable control of contact force. The Lyapunov theorem is used to establish the asymptotic stability of the suggested controller. We performed multiple simulations and polishing tests to validate the effectiveness of the proposed method. The force-based polishing method exhibited a 65% increase in the average surface quality. In summary, the experimental results indicate that the suggested design and control approach may effectively maintain a stable contact force and provide high-quality machining while polishing a workpiece with an irregular plane and curved surface contour.